Year % of tax revenue 2001 0.001303167954570423 2002 4.755177544301731E-06 2007 8.88746563226243E-05 2011 0.001571374336565755 2012 0.07063082059761067 2013 0.027835568197840065 2014 0.0028871505082763834 2015 0.00303528616425663 2016 0.019751655847148518 2017 0.01330586160711074 2018 0.016602907027886072 2019 0.05081291853287074 2020 0.03486325306811493 2021 0.000218306036918069